Developing Fire Management Strategies for Tejon Ranch

Developing Fire Management Strategies for Tejon Ranch
Sean Baumgarten, Ashley Gilreath, Ellie Knecht, Adam Livingston, Nicole Phipps, and Andrew Prosser
Faculty Advisor: Frank Davis
Client: Tejon Ranch Conservancy
Recommendations
Grasslands
• Goals: Maintain mosaic of ages; mitigate spread of
fire regime-altering invasive species
• Concerns: Increased sedimentation; high fuel loads;
increased ignitions
• Recommendations: Assess feasibility of tamarisk
removal; survey fuel loads in high risk areas
Riparian Systems
Why is fire management important?
• Goals: Prevent type conversion; promote oak
regeneration; maintain mature overstory
• Concerns: Fuel build-up; lack of oak regeneration
• Recommendations: Monitor fuel loads and oak
recruitment; avoid active fuel treatments unless
compelling need exists
In addition to its implications for human safety, fire has significant effects on
wildlife habitat, vegetation composition and overall ecological functioning. Some
of the Ranch s ecosystems are adapted to periodic wildfires, while others are
relatively fire-intolerant. In either case, changes in the frequency and severity of
wildfires can have a major impact on the Ranch.
Oak Woodlands
Identify post-European
settlement changes to fire
regimes.
Identify key uncertainties
pertaining to the fire ecology
and management of the
Ranch’s major ecological
communities.
Evaluate the impact of
alternative management
strategies, climate change,
and development on
vegetation communities and
fire regimes.
Develop fire management
recommendations for each
major ecosystem type.
12 11 10 9 8 7 6 5 4 3 2 1 1950 1960 1970 1980 1990 2000 2010 Year of fire Size and season of fires occurring on Tejon Ranch. The size of each circle reflects the relaKve area burned. 50 45 40 35 30 25 20 15 10 5 0 1950 1960 1970 1980 1990 Chaparral
• Goals: Prevent type conversion; promote mature,
open forest structure
• Concerns: Increased forest density; dangerous fuel
dynamics; risk of extensive stand replacing fires
• Recommendations: Monitor fuel loads and forest
density; consider thinning treatments and exclusion
of grazing
Conifer Forests
Final Report
Fire return interval departure (FRID) map for Tejon Ranch. Future Fire Frequency
•  Modeling and cost
analysis for selected
management options
Research
historical fire
regimes and
management
options
Quantify changes in
size, seasonality and
ignition source of fires
on the Ranch, and
map areas burning
less frequently than
historical norm
Conclusions
•  Analysis of changes in
the Ranch s fire regimes
•  Management goals,
concerns and specific
recommendations for each
major ecological
community
2010 To better understand the nature and
occurrence of fires on the Ranch, we
analyzed fire size, frequency, and source of
ignition for fires occurring on the Ranch
since 1950. Fire frequency increased over
the past 60 years. In addition, average fire
size was approximately two times larger
since 1980 than in the period between 1950
and 1979. As a result, the total area burned
since 1980 is approximately 13 times greater
than the area impacted by fire prior to 1980.
There is also some indication that fires may
be occurring outside of the historical fire
season. The majority of fires with identified
ignition sources are the result of human
activities, such as vehicle or equipment use.
Increases in fire size, frequency, and season
on the Ranch may be the result of these
anthropogenic ignitions as well as climate
change.
In order to understand how the Ranch is departing
from historical fire regimes̶and, specifically, to
take into account areas that are burning less
frequently than historical norms̶we used fire
return interval departure (FRID) analysis. The
map on the left illustrates what we found: areas in
yellow and orange are burning somewhat less
frequently than they did historically, and areas in
red are burning much less frequently. Olivecolored areas are burning as often as they did in
the past, or more often. It is important to note,
however, that many of the high-departure (i.e.,
red) areas are grasslands, an ecological
community where there is considerable uncertainty
about historical fire regimes.
Joshua Tree Woodlands and Mojavean Scrub
Model impact
of selected
management
options
2000 Year Number of fires per year in the region. A Poisson regression was used to represent the relaKonship between number of fires and year. • Goals: Reduce risk of wildfire; prevent loss of
shrub species diversity
• Concerns: Proximity to sensitive desert
vegetation; frequent burning threatening obligate
seeding species
• Recommendations: Continue fire suppression;
no strong case for prescribed burns
• Goals: Prevent type conversion
• Concerns: Disturbance; invasive/wildfire cycle
• Recommendations: Monitor invasive annual
grasses such as Bromus tectorum; continue fire
suppression
Methods
Fire Size, Seasonality and Ignition
Current Fire Frequency
Photo Credit: Tejon Oaks 2011 Objectives
Results
Month of fire (Jan-­‐Dec) • Goals: Preserve native species; maintain
biodiversity
• Concerns: Proliferation of nonnative species;
impacts of fire and grazing on community
composition
• Recommendations: Continue fire suppression;
consider burning test plots if native species declining
Nestled at the crossroads of four major ecological
regions and spanning more than 270,000 acres, Tejon
Ranch is the largest contiguous piece of private land
in California, and an important locus of biodiversity.
Under a recent agreement, the vast majority of the
Ranch will be set aside for permanent conservation.
Protected areas will be managed by the Tejon Ranch
Conservancy, whose mission is to preserve,
enhance, and restore the native biodiversity and
ecosystem values of the Ranch and Tehachapi Range
for the benefit of California s future generations. A
particular challenge that the Conservancy faces is
how to manage fire, which is both a serious threat and
an important ecological process.
Number of fires (>10 acres) Background
Our analysis suggests that the Ranch s fire regimes may be changing. Fires on the Ranch
have become more numerous in recent years and, unlike in the region as a whole, they may
be increasing in size. But these changes appear to be unevenly distributed: even with
greater numbers of fires in recent decades, parts of the Ranch are actually burning less
frequently than historical norms. As climate change intensifies, and continued development
leads to more anthropogenic ignitions, the Ranch s fire regimes may continue to shift.
Annual probability of burning under current climate scenarios. We utilized a spatially explicit forest landscape model
called LANDIS-II to simulate the possible effects of
development, climate change, and fire management
strategies across a portion of the Ranch. Modeling
these factors allowed us to better understand their
interactive effects on fire and ecosystem succession,
and provided insights into how the Ranch may change
in the future. Our results indicate that climate change
may lead to an increase in the annual probability of
fire, particularly in areas already prone to frequent fire.
Management treatments in conifer forests (thinning
and prescribed burning) had no significant effect on
fire frequency.
Understanding these shifts is likely to require improved monitoring of fuel conditions. With
the exception of fire suppression, which appears to be appropriate across the Ranch,
adaptation measures will vary by ecological community. In some communities, such as
montane conifer forests, active management may be necessary to prevent type conversion.
Where active management is necessary, lighter treatments over a larger area are likely to
be more cost-effective than intensive thinning in a smaller area.
Average annual probability of fire under current climate, and under two climate change scenarios. Acknowledgments: Frank Davis (Faculty Advisor); James Frew and Christina Tague (Advisors); Thomas H. Maloney, Michael D. White, and Phoebe Prather (Clients); Tejon Ranch Conservancy and the ACE Group (Funders); Carla D Antonio, Charles Jones, Bruce Kendall, Gary Libecap, Paula Schiffman and Alexandra Syphard (Advice on Particular Questions)
Website: http://fiesta.bren.ucsb.edu/~tejonfire/index.html